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Mathematical Problems in Engineering
Volume 2014 (2014), Article ID 162561, 18 pages
Research Article

A Novel Integral 5-DOFs Hybrid Magnetic Bearing with One Permanent Magnet Ring Used for Turboexpander

1School of Instrument Science and Opto-Electronics Engineering, Beihang University, Beijing 100191, China
2Key Laboratory of Fundamental Science for National Defense of Novel Inertial Instrument and Navigation System Technology, Beijing 100191, China
3Science and Technology on Inertial Laboratory, Beijing 100191, China

Received 9 September 2013; Revised 20 January 2014; Accepted 6 February 2014; Published 7 May 2014

Academic Editor: Hector Puebla

Copyright © 2014 Bangcheng Han et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We propose a novel combined five-degrees-of-freedom (5-DOFs) hybrid magnetic bearing (HMB) with only one permanent magnet ring (PMR) used for turboexpanders. It has two radial magnetic bearing (RMB) units; each has four poles and one thrust magnetic bearing (TMB) to control 5-DOFs. Based on one PMR, the bias flux of the two radial magnetic bearing units and the one thrust magnetic bearing unit is constructed. As a result, ultra-high-speed, lower power loss, small size, and low cost can be achieved. Furthermore, the equivalent magnetic circuit method and 3D finite element method (FEM) are used to model and analyze the combined 5-DOFs HMB. The force-current, force-position, torque-coil currents, the torque-angle position, and the stiffness models of the combined 5-DOFs HMB are given. Moreover, its coupling problems between the RMB units and the AMB unit are also proposed in this paper. An example is given to clarify the mathematical models and the coupling problems, and the linearized models are proposed for the follow-up controller design.